1. Field of the Invention
This invention relates to polymer dispersions in polyols and more particularly relates to dispersions of polymers made from various vinyl monomers in the presence of polyols as the dispersing media.
2. Related Art in the Field
The use of a polyol in the preparation of polyurethanes by reaction of the polyol with a polyisocyanate in the presence of a catalyst and perhaps other ingredients is well known. Conventional polyols for flexible polyurethane foams are usually made by the reaction of a polyhydric alcohol with an alkyene oxide, usually ethylene oxide and/or propylene oxide, to a molecular weight of about 2,000 to 3,000 and above. These polyols are then reacted with polyisocyanate in the presence of water or other blowing agents such as fluorocarbons to obtain polyurethane foams. Polyols have been modified in many ways in attempts to improve the properties of the resulting polyurethane.
One common method of modifying polyols involves the use of polymers as the dispersed phase. One type is made by polymerizing vinyl monomers such as acrylonitrile and styrene in polyols. Another type includes the polymerization of vinyl monomers in polyol-isocyanate addition products. Another type involves the preparation of polyurea polymers by the reaction of diamines with diisocyanates in a polyol.
For example, U.S. Pat. No. 3,008,917 to Park, et al. teaches adding an unsaturated liquid monomer such as styrene to a polyester-isocyanate adduct which itself contains vinyl unsaturation. The resulting mixture is then copolymerized through the unsaturated linkages. U.S. Pat. No. 3,304,273 to Stamberger discloses a polymer polyol made by mixing a minor amount of a film-forming polymer having radicals reactive with the --N.dbd.C.dbd.O radicals of an organic polyisocyanate (such as polymers of acrylic acid, allyl alcohol, styrene, butadiene, etc.) in with a major amount of a solvent which also contains radicals reactive with an isocyanate group but has little or no ethylenic unsaturation (such as a polyol). Similar polymer polyols where the dispersed polymers consist of polymerized unsaturated monomers such as methacrylonitrile, styrene, etc., particularly copolymers using more than one kind of unsaturated monomer are disclosed in U.S. Pat. No. 3,383,351 to Stamberger. These materials are useful in preparation of polyurethane products.
U.S. Pat. No. 4,104,236 to Simroth reveals a liquid polymer polyol composition containing 45-90 wt. % of a polyoxypropylene polyol having a molecular weight of at least 1500 and 55 to 10 wt. % of a polymer. The polymer consists of 60 to 90 wt. % polymerized acrylonitrile and 40 to 10 wt. % of polymerized styrene. Polyurethane foams having high load-bearing properties and solid polyurethane elastomers having a high modulus were made from these materials. A polymer polyol consisting of 45 to 95 wt. % of a poly(oxypropyleneoxyethylene) polyol having a hydroxyl number of 20 to 60, an oxyethylene cap of 10 to 30 wt. % and an internal oxyethylene content of 5 to 60 wt. % and from 5 to 60 wt. % of a polymerized vinyl monomer (such as a co-polymer of styrene and acrylonitrile) is taught in U.S. Pat. No. 4,125,505 to Critchfield, et al. Further, U.S. Pat. No. 4,148,840 to Shah, et al. discloses polymer polyol compositions made by polymerizing one or more ethylenically unsaturated monomers in a polyol.
High resilience urethane foams may be prepared from tolylene diisocyanate and novel polymer polyol compositions made with acrylonitrile and vinylidene chloride monomers according to U.S. Pat. No. 4,214,055 to Seefried, et al. The acrylonitrile-vinylidene chloride polymer polyol compositions apparently enhance the load-bearing properties and decrease the flammability of the resultant foams. U.S. Pat. No. 4,226,756 to Critchfield, et al. teaches that polyol/vinyl polymer blends made by polymerizing acrylonitrile, styrene and/or methyl methacrylate in the presence of polyethylene-polypropylene glycols are useful in producing polyurethanes. Polymer stabilizers made by polymerizing 30:70 acrylonitrile-styrene mixtures with polypropylene glycol mono-butyl ether methacrylate are disclosed by U.S. Pat. No. 4,242,249 to Van Cleve, et al. as useful stabilizers for polyol-vinyl monomer reaction products.
U.S. Pat. No. 3,325,421 to Miller, et al. describes polyurea polymer polyols made by reaction of diamines with diisocyanate using a polyol as the dispersing media. See also British Pat. No. 899,413, which discloses the emulsion polymerization of vinyl monomers in a suspending agent where the agent is made by condensing polyethylene glycol with the diglycidyl ether of bisphenol A.
The polyols found to be useful as the dispersing media in this invention are polyols modified with epoxy resins. Generally, a polyepoxide is added into the reaction of a polyol initiator with mixtures of alkylene oxides before the alkylene oxide addition is complete. For example, see U.S. Pat. Nos. 4,316,991 and 4,373,034 both to Speranza, et al., incorporated by reference herein.